A thyristor starting device includes a converter which converts three-phase alternating current (AC) power into direct current (DC) power, a DC reactor which smooths a DC current, and an inverter which converts the DC power provided from the converter through the DC reactor into three-phase AC power having a desired frequency, and provides the three-phase AC power to a synchronous machine. As disclosed for example in Japanese Patent Laying-Open No. 62-262670 (PTD 1), the thyristor starting device includes an AC current detector which detects a three-phase AC current to be input to the converter, an AC voltage detector which detects a three-phase AC voltage output from the inverter, and a control circuit which controls the converter and the inverter based on detection results of the AC current detector and the AC voltage detector. By controlling the three-phase AC power to be provided to the synchronous machine, the synchronous machine in a stopped state can be started and rotationally driven at a prescribed rotation speed.